U.S. patent application number 13/946926 was filed with the patent office on 2015-01-22 for barium titanate toner additive.
The applicant listed for this patent is XEROX CORPORATION. Invention is credited to Thomas Edward Enright, Richard A. Klenkler, Thomas R. Pickering, Richard Philip Nelson Veregin.
Application Number | 20150024318 13/946926 |
Document ID | / |
Family ID | 52343840 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150024318 |
Kind Code |
A1 |
Enright; Thomas Edward ; et
al. |
January 22, 2015 |
BARIUM TITANATE TONER ADDITIVE
Abstract
A toner composition includes toner particles and an additive
disposed on an exterior surface of the toner particles, the
additive includes uncoated barium titanate particles, the toner
composition is substantially free of one or more rare earth
compounds and the uncoated barium titanate particles are present in
a sufficient amount to reduce bias charge roller contamination.
Inventors: |
Enright; Thomas Edward;
(Tottenham, CA) ; Pickering; Thomas R.; (Webster,
NY) ; Klenkler; Richard A.; (Oakville, CA) ;
Veregin; Richard Philip Nelson; (Mississauga, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XEROX CORPORATION |
Norwalk |
CT |
US |
|
|
Family ID: |
52343840 |
Appl. No.: |
13/946926 |
Filed: |
July 19, 2013 |
Current U.S.
Class: |
430/108.6 |
Current CPC
Class: |
G03G 9/0804 20130101;
G03G 9/0819 20130101; G03G 9/09708 20130101; G03G 9/09716 20130101;
G03G 9/09725 20130101; G03G 9/0806 20130101 |
Class at
Publication: |
430/108.6 |
International
Class: |
G03G 9/097 20060101
G03G009/097; G03G 9/08 20060101 G03G009/08 |
Claims
1. A toner composition comprising toner particles and an additive
disposed on an exterior surface of the toner particles, the
additive comprising uncoated barium titanate particles, wherein the
toner composition is substantially free of one or more rare earth
compounds and wherein the uncoated barium titanate particles are
present in a sufficient amount to reduce bias charge roller
contamination.
2. The toner composition of claim 1, wherein the uncoated barium
titanate particles are present in a range of from about 0.25 weight
percent to about 0.75 weight percent.
3. The toner composition of claim 2, wherein the uncoated barium
titanate particles are present in a range of from about 0.40 weight
percent to about 0.60 weight percent.
4. The toner composition of claim 1, wherein the uncoated barium
titanate particles have an average particle size in a range of from
about 0.2 microns to about 1.5 microns.
5. The toner composition of claim 1, wherein the uncoated barium
titanate particles are irregular in shape or substantially
spherical.
6. The toner composition of claim 1, wherein the toner particles
are made by an emulsion/aggregation coalescence process.
7. The toner composition of claim 1, wherein the additives further
comprise at least one of surface-treated silica, surface-treated
titania, spacer particles, and combinations thereof.
8. The toner composition of claim 7, wherein the surface-treated
silica is present in an amount of from about 1.6 weight percent to
about 2.8 weight percent based on the weight of the toner
particle.
9. The toner composition of claim 7, wherein the surface-treated
silica has an average particle size of from about 20 to about 50
nm.
10. The toner composition of claim 7, wherein the surface-treated
titania is present in an amount of from about 0.5 weight percent to
about 2.5 weight percent based on the weight of the toner
particle.
11. The toner composition of claim 7, wherein the surface-treated
titania has an average particle size of from about 20 to about 50
nm.
12. The toner composition of claim 7, wherein the spacer particles
are present in an amount of from about 0.6 weight percent to about
1.8 weight percent based on the weight of the toner particle.
13. The toner composition of claim 7, wherein the spacer particles
have an average particle size of from about 100 to about 150
nm.
14. The toner composition of claim 7, wherein the spacer particles
are selected from the group consisting of latex particles, polymer
particles, and sol-gel silica particles.
15. A toner composition comprising toner particles and additives
disposed on an exterior surface of the toner particles, the
additives comprising: about 0.30 weight percent to about 0.50
weight percent of uncoated barium titanate particles;
surface-treated silica; surface-treated titania; and spacer
particles; wherein the toner composition is substantially free of
one or more rare earth compounds.
16. The toner composition of claim 15, wherein the uncoated barium
titanate particles have an average particle size in a range of from
about 0.2 microns to about 1.5 microns.
17. The toner composition of claim 15, wherein the toner particles
are made by an emulsion/aggregation coalescence process.
18. A toner composition comprising toner particles and additives
disposed on an exterior surface of the toner particles, the
additives comprising: barium titanate particles have an average
particle size in a range of from about 0.2 microns to about 1.5
microns; surface-treated silica; surface-treated titania; and
spacer particles; wherein the toner composition is substantially
free of one or more rare earth compounds and wherein the uncoated
barium titanate particles are present in a sufficient amount to
reduce bias charge roller contamination.
19. The toner composition of claim 18, the uncoated barium titanate
particles are present in a range of from about 0.30 weight percent
to about 0.50 weight percent.
20. The toner composition of claim 18, wherein the toner particles
are made by an emulsion/aggregation coalescence process.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly owned and co-pending, U.S.
patent application Ser. No. ______ (not yet assigned) entitled
"SILICON CARBIDE TONER ADDITIVE" to Enright et al., electronically
filed on the same day herewith (Attorney Docket No.
20121204-420033), U.S. patent application Ser. No. ______ (not yet
assigned) entitled "ZIRCONIUM OXIDE TONER ADDITIVE" to Enright et
al., electronically filed on the same day herewith (Attorney Docket
No. 20121205-420029), U.S. patent application Ser. No. ______ (not
yet assigned) entitled "TONER ADDITIVES TO PREVENT BIAS ROLLER
CONTAMINATION" to Veregin et al., electronically filed on the same
day herewith (Attorney Docket No. 20121207-420032), the disclosures
of which are hereby incorporated by reference in its entirety.
FIELD
[0002] Embodiments disclosed herein relate to toner compositions.
In particular, embodiments disclosed herein relate to toner
compositions comprising barium titanate additives that mitigate
bias charge roller (BCR) contamination.
BACKGROUND
[0003] Image forming devices including copiers, printers, facsimile
machines, scanners and the like, include a photoreceptor or
photoconductor component, the surface of which is typically charged
to a uniform electrical potential and then selectively exposed to
light in a pattern corresponding to an original image. Those areas
of the photoconductive surface exposed to light are discharged,
thus forming a latent electrostatic image on the photoconductive
surface.
[0004] A developer material, such as toner, having an electrical
charge such that the toner is attracted to the photoconductive
surface, is brought into contact with the photoreceptor's
photoconductive surface. A recording sheet, such as a blank sheet
of paper or a transfer belt, is then brought into contact with the
photoconductive surface and the toner thereon is transferred to the
recording sheet in the form of the latent electrostatic image. The
recording sheet may then be heated thereby permanently fusing the
toner.
[0005] A photoconductive drum, for example, is typically charged to
a substantial voltage, such as a voltage greater than 1,000 V DC.
This voltage could be either positive or negative with respect to
ground, depending upon the charging system and the chemicals used
in the photoconductive drum material. Additionally, an AC voltage
superimposed on the DC voltage may be employed.
[0006] For a photoconductive drum to achieve this substantially
large voltage, it is typical for a bias charge roller (BCR) to be
placed into contact with the surface of the photoconductive drum.
The bias charge roller typically comprises a moderately
electrically conductive component, or a semiconductive component,
which has an electrically conductive center that receives a high
voltage from a high voltage power supply. As voltage is received at
the electrically conductive center, this voltage charges the entire
bias charge roller, including its outer cylindrical surface. This
high voltage at the cylindrical surface of the BCR is then passed
onto the outer surface of the photoconductive drum as the drum
rotates.
[0007] The ability of the bias charge roller to charge the
photoconductive drum decreases over its life due to roller
characteristics and contamination of the surface of the roller.
This decrease in ability to charge may, over time, impact the
ability of the photoconductive drum to produce accurate prints.
Consequently, it is desirable to reduce buildup of contamination
that occurs on the surface of the bias charge roller which may
subsequently decrease bias charge roller life or reduce print
quality.
SUMMARY
[0008] According to embodiments illustrated herein, there are
provided toner compositions comprising barium titanate that exhibit
improved ability in mitigating bias charge roller
contamination.
[0009] In some aspects, embodiments disclosed herein relate to a
toner composition comprising toner particles and an additive
disposed on an exterior surface of the toner particles, the
additive comprising uncoated barium titanate particles, wherein the
toner composition is substantially free of one or more rare earth
compounds and wherein the uncoated barium titanate particles are
present in a sufficient amount to reduce bias charge roller
contamination.
[0010] In some aspects, embodiments disclosed herein relate to a
toner composition comprising toner particles and additives disposed
on an exterior surface of the toner particles, the additives
comprising about 0.30 weight percent to about 0.50 weight percent
of uncoated barium titanate particles, surface-treated silica,
surface-treated titania, and spacer particles, wherein the toner
composition is substantially free of one or more rare earth
compounds.
[0011] In some aspects, embodiments disclosed herein relate to a
toner composition comprising toner particles and additives disposed
on an exterior surface of the toner particles, the additives
comprising barium titanate particles have an average particle size
in a range of from about 0.2 microns to about 1.5 microns,
surface-treated silica, surface-treated titania, and spacer
particles, wherein the toner composition is substantially free of
one or more rare earth compounds and wherein the uncoated barium
titanate particles are present in a sufficient amount to reduce
bias charge roller contamination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a better understanding of the present embodiments,
reference may be made to the accompanying figures.
[0013] FIG. 1 shows a print pattern for a machine test (50% AC
Process Black; actual density per color about 93% fill) used in
generating the data of FIGS. 2-4.
[0014] FIG. 2 shows photographs of photoreceptor-BCR contamination
at the end of a 5000 print machine test. Top panel shows effect
with no additive. Middle panel shows effect with cerium oxide.
Bottom panel show effect with barium titanate.
[0015] FIG. 3A shows a plot of toner charging (At) at print
intervals in a machine test with additive-containing toner
compositions comprising cerium oxide (diamond) and barium titanate
(triangle).
[0016] FIG. 3B shows a plot of toner concentration (TC) at print
intervals in a machine test with additive-containing toner
compositions comprising cerium oxide (diamond) and barium titanate
(triangle).
[0017] FIG. 4 shows photographs comparing various additives
screened for prevention of BCR contamination.
DETAILED DESCRIPTION
[0018] In the following description, it is understood that other
embodiments may be utilized and structural and operational changes
may be made without departure from the scope of the present
embodiments disclosed herein.
[0019] Cerium dioxide (Mirek E10 brand CeO.sub.2, available from
Mitsui Mining and Smelting Co., Ltd., Tokyo, JP) is a rare earth
material that is commonly employed as a toner additive, including
toner compositions comprising toner particles produced via emulsion
aggregation. It has been postulated that cerium dioxide may serve
as a photoreceptor cleaning agent, specifically for machines that
have a photoreceptor cleaning blades as part of their architecture.
Recent increases in the cost of cerium and other rare earth
elements have prompted a search for replacement additives that
address filming on the photoreceptor surface while reducing
costs.
[0020] As disclosed herein, a number of alternative additives were
selected based on their polishing capabilities along with similar
physical properties to CeO.sub.2, including inter alia, similar
particle size. It was discovered that all of these alternative
additives had generally good photoreceptor filming prevention
capabilities. However, it was surprisingly discovered that
CeO.sub.2 serves a secondary function previously unrecognized in
the art. As indicated in the Examples below, only certain
candidates also prevented contamination of the bias charging roll
(BCR) in the imaging system. Thus, while all of the candidates
prevented photoreceptor filming, results varied in their ability to
control BCR contamination. As BCR contamination is one of the main
failures of machines in the field and it causes non-uniform
photoreceptor charging that results in print defects, embodiments
disclosed herein advantageously provide toner compositions which
prevent both photoreceptor filming and reduce or prevent BCR
contamination.
[0021] In accordance with embodiments disclosed herein, barium
titanate may be used to replace cerium dioxide as a toner additive
as a photoreceptor cleaning agent while also providing protection
against BCR contamination. Preventing bias charging roll
contamination results in significant cost savings, while the
substitution of barium titanate in lieu of cerium dioxide appears
to have no negative impacts on other toner properties.
[0022] In some embodiments, there are provided toner compositions
comprising toner particles and additives disposed on exterior
surfaces of the toner particles, the additives comprising uncoated
barium titanate particles, wherein the toner compositions are
substantially free of one or more rare earth compounds and wherein
the uncoated barium titanate particles are present in a sufficient
amount to reduce bias charge roller contamination.
Barium Titanate
[0023] In some embodiments, toner compositions disclosed herein
comprise additives comprising uncoated barium titanate. As used in
conjunction with barium titanate particles, "uncoated" refers to
barium titanate particles specifically lacking hydrophobic
modification, polymer encapsulation, surfactant modification, and
the like. As an additive exterior to the surface of the toner
particles the uncoated barium titanate particles are also not
embedded in the toner particles. In practice, the uncoated barium
titanate particles are configured to freely dissociate from the
toner particles.
[0024] In some embodiments, the uncoated barium titanate particles
are present in a range of from about 0.25 to about 0.75, from about
0.40 to about 0.60, or from about 0.45 to about 0.55 weight
percent, or about 0.50 weight percent of the total weight of the
blended toner particles.
[0025] Without being bound by theory, it has been postulated that
the barium titanate particles disclosed herein function by
dissociating from the toner particles allowing them to freely move
to the photoreceptor where they may limit various toner components
from moving to the BCR. Because the barium titanate particles do
not remain on the toner particles, toner charging, flow or other
development properties are unaffected. Thus, the treatment and/or
coating of the barium titanate to control charge, adhesion or water
adsorption is unnecessary. Such unprocessed barium titanate can
provide beneficial cost savings. Moreover, treatments and/or
coatings, if they were employed on the barium titanate disclosed
herein, could reduce the density of the particles and result in
softer barium titanate particles, which could interfere with its
ability to function on the photoreceptor to improve BCR cleaning.
Thus, in particular embodiments, the barium titanate particles are
neither treated nor coated in any manner.
[0026] In some embodiments, the uncoated barium titanate particles
have an average particle size in a range of from about 0.2 microns
to about 1.5 microns, or from about 0.4 to about 0.8 microns, or
from about 0.5 to about 0.7 microns, including any values between
the recited ranges. In some embodiments, the uncoated barium
titanate particles may be irregular in shape or substantially
spherical.
[0027] The toner compositions disclosed herein include externally
applied additives which include the uncoated barium titanate
particles described herein above. In some embodiments, the
additives may further comprise at least one of surface-treated
silica, surface-treated titania, spacer particles, and combinations
thereof. The additives may be packaged together as an additives
package to add to the toner composition. That is, the toner
particles are first formed, followed by mixing of the toner
particles with the materials of the additives package. The result
is that some components of the additive package may coat or adhere
to external surfaces of the toner particles, rather than being
incorporated into the bulk of the toner particles. The uncoated
barium titanate, however, is not specifically designed to adhere to
the toner particles per se as they ideally are free flowing to
provide the requisite BCR contamination prevention, in accordance
with embodiments disclosed herein.
Silica
[0028] Any suitable untreated silica or surface treated silica can
be used. Such silicas can be used alone, as only one silica, or can
be used in combination, such as two or more silicas. Where two or
more silicas are used in combination, it is may be beneficial,
although not required, that one of the surface treated silicas be a
decyl trimethoxysilane (DTMS) surface treated silica. In particular
embodiments, the silica of the decyl trimethoxysilane (DTMS)
surface treated silica may be a fumed silica.
[0029] Conventional surface treated silica materials are known and
include, for example, TS-530 from Cabosil Corporation, with an 8
nanometer particle size and a surface treatment of
hexamethyldisilazane; NAX50, obtained from Evonik Industries/Nippon
Aerosil Corporation, coated with HMDS; H2050EP, obtained from
Wacker Chemie, coated with an amino functionalized
organopolysiloxane; CAB-O-SIL.RTM. fumed silicas such as for
example TG-709F, TG-308F, TG-810G, TG-811F, TG-822F, TG-824F,
TG-826F, TG-828F or TG-829F with a surface area from 105 to 280
m.sup.2/g obtained from Cabot Corporation; and the like. Such
conventional surface treated silicas are applied to the toner
surface for toner flow, triboelectric charge enhancement, admix
control, improved development and transfer stability, and higher
toner blocking temperature.
[0030] In other embodiments, other surface treated silicas can also
be used. For example, a silica surface treated with
polydimethylsiloxane (PDMS), can also be used. Specific examples of
suitable PDMS-surface treated silicas include, for example, but are
not limited to, RY50, NY50, RY200, RY200S and R202, all available
from Nippon Aerosil, and the like.
[0031] In some embodiments, the silica additive is a
surface-treated silica. When so provided, the surface treated
silica may be the only surface treated silica present in the toner
composition. As described below, the additive package may also
beneficially include large-sized sol-gel silica particles as spacer
particles, which is distinguished from the surface treated silica
described herein. Alternatively, for example where small amounts of
other surface treated silicas are introduced into the toner
composition for other purposes, such as to assist toner particle
classification and separation, the surface treated silica is the
only xerographically active surface treated silica present in the
toner composition. Any other incidentally present silica thus does
not significantly affect any of the xerographic printing
properties. In some embodiments, the surface treated silica is the
only surface treated silica present in the additive package applied
to the toner composition. Other suitable silica materials are
described in, for example, U.S. Pat. No. 6,004,714, the entire
disclosure of which is incorporated herein by reference.
[0032] In some embodiments, the silica additive may be present in
an amount of from about 1 to about 4 percent by weight, based on a
weight of the toner particles without the additive or, in an amount
of from about 0.5 to about 5 parts by weight additive per 100 parts
by weight toner particle or from about 1.6 weight percent to about
2.8 weight percent or from about 1.5 or from about 1.8 to about 2.8
or to about 3 percent by weight.
[0033] In some embodiments, the silica has an average particle size
of from about 10 to about 60 nm, or from about 15 to about 55 nm,
or from about 20 to about 50 nm.
Titania
[0034] Another component of the additive package is a titania, and
in embodiments a surface treated titania. In some embodiments, the
surface treated titania used in embodiments is a hydrophobic
surface treated titania.
[0035] Conventional surface treated titania materials are known and
include, for example, metal oxides such as TiO.sub.2, for example
MT-3103 from Tayca Corp. with a 16 nanometer particle size and a
surface treatment of decylsilane; SMT5103, obtained from Tayca
Corporation, comprised of a crystalline titanium dioxide core
MT500B coated with DTMS; P-25 from Degussa Chemicals with no
surface treatment; an isobutyltrimethoxysilane (i-BTMS) treated
hydrophobic titania obtained from Titan Kogyo Kabushiki Kaisha (IK
Inabata America Corporation, New York); and the like. Such surface
treated titania are applied to the toner surface for improved
relative humidity (RH) stability, triboelectric charge control and
improved development and transfer stability.
[0036] While any of the conventional and available titania
materials can be used, it may be beneficial that specific surface
treated titania materials be used, which have been found to
unexpectedly provide superior performance results in toner
compositions. Thus, while any of the surface treated titania may be
used in the additive package, in some embodiments the material may
be a "large" surface treated titania (i.e., one having an average
particle size of from about 30 to about 50 nm, or from about 35 to
about 45 nm, particularly about 40 nm). In particular, it has been
found that the surface treated titania provides one or more of
better cohesion stability of the toners after aging in the toner
housing, and higher toner conductivity, which increases the ability
of the system to dissipate charge patches on the toner surface.
[0037] Specific examples of suitable surface treated titanias
include, for example, but are not limited to, an
isobutyltrimethoxysilane (i-BTMS) treated hydrophobic titania
obtained from Titan Kogyo Kabushiki Kaisha (IK Inabata America
Corporation, New York); SMT5103, obtained from Tayca Corporation or
Evonik Industries, comprised of a crystalline titanium dioxide core
MT500B coated with DTMS (decyltrimethoxysilane); and the like. The
decyltrimethoxysilane (DTMS) treated titania is particularly
beneficial, in some embodiments.
[0038] In some embodiments, only one titania, such as surface
treated titania, is present in the toner composition. That is, in
some embodiments, only one kind of surface treated titania is
present, rather than a mixture of two or more different surface
treated titanias.
[0039] The titania additive may be present in an amount of from
about 0.5 to about 4 percent by weight, based on a weight of the
toner particles without the additive, or about 0.5 to about 2.5, or
about 0.5 to about 1.5, or about 2.5 or to about 3 percent by
weight. In some embodiments, the surface-treated titania has an
average particle size of from about 10 to about 60 nm, or from
about 20 to about 50 nm, such as about 40 nm.
Spacer Particles
[0040] Another component of the additive package is a spacer
particle. In some embodiments, the spacer particles have an average
particle size of from about 100 to about 150 nm. In some
embodiments, the spacer particles are selected from the group
consisting of latex particles, polymer particles, and sol-gel
silica particles. In some embodiments, the spacer particle used in
embodiments is a sol-gel silica.
[0041] Spacer particles, particularly latex or polymer spacer
particles, are described in, for example, U.S. Patent Application
Publication No. 2004/0137352, the entire disclosure of which is
incorporated herein by reference.
[0042] In some embodiments, the spacer particles are comprised of
latex particles. Any suitable latex particles may be used without
limitation. As examples, the latex particles may include rubber,
acrylic, styrene acrylic, polyacrylic, fluoride, or polyester
latexes. These latexes may be copolymers or crosslinked polymers.
Specific examples include acrylic, styrene acrylic and fluoride
latexes from Nippon Paint (e.g. FS-101, FS-102, FS-104, FS-201,
FS-401, FS-451, FS-501, FS-701, MG-151 and MG-152) with particle
diameters in the range from 45 to 550 nm, and glass transition
temperatures in the range from 65.degree. C. to 102.degree. C.
[0043] These latex particles may be derived by any conventional
method in the art. Suitable polymerization methods may include, for
example, emulsion polymerization, suspension polymerization and
dispersion polymerization, each of which is well known to those
versed in the art. Depending on the preparation method, the latex
particles may have a very narrow size distribution or a broad size
distribution. In the latter case, the latex particles prepared may
be classified so that the latex particles obtained have the
appropriate size to act as spacers as discussed above. Commercially
available latex particles from Nippon Paint have very narrow size
distributions and do not require post-processing classification
(although such is not prohibited if desired).
[0044] In a further embodiment, the spacer particles may also
comprise polymer particles. Any type of polymer may be used to form
the spacer particles of this embodiment. For example, the polymer
may be polymethyl methacrylate (PMMA), e.g., 150 nm MP1451 or 300
nm MP116 from Soken Chemical Engineering Co., Ltd. with molecular
weights between 500 and 1500K and a glass transition temperature
onset at 120.degree. C., fluorinated PMMA, KYNAR.RTM.
(polyvinylidene fluoride), e.g., 300 nm from Pennwalt,
polytetrafluoroethylene (PTFE), e.g., 300 nm L2 from Daikin, or
melamine, e.g., 300 nm EPOSTAR-S.RTM. from Nippon Shokubai.
[0045] In some embodiments, the spacer particles on the surfaces of
the toner particles are believed to function to reduce toner
cohesion, stabilize the toner transfer efficiency and
reduce/minimize development falloff characteristics associated with
toner aging such as, for example, triboelectric charging
characteristics and charge through. These additive particles
function as spacers between the toner particles and carrier
particles and hence reduce the impaction of smaller conventional
toner external surface additives, such as the above-described
silica and titania, during aging in the development housing. The
spacers thus stabilize developers against disadvantageous burial of
conventional smaller sized toner additives by the development
housing during the imaging process in the development system. The
spacer particles function as a spacer-type barrier, and therefore
the smaller toner additives are shielded from contact forces that
have a tendency to embed them in the surface of the toner
particles. The spacer particles thus provide a barrier and reduce
the burial of smaller sized toner external surface additives,
thereby rendering a developer with improved flow stability and
hence excellent development and transfer stability during
copying/printing in xerographic imaging processes. The toner
compositions of the present disclosure thereby exhibit an improved
ability to maintain their DMA (developed mass per area on a
photoreceptor), their TMA (transferred mass per area from a
photoreceptor) and acceptable triboelectric charging
characteristics and admix performance for an extended number of
imaging cycles.
[0046] The spacer particles may be present in an amount of from
about 0.3 to about 2.5 percent by weight, based on a weight of the
toner particles without the additive, or from about 0.6 to about
1.8, or from about 0.5 to about 1.8 percent by weight.
[0047] In some embodiments, the spacer particles are large sized
silica particles. Thus, in some embodiments, the spacer particles
have an average particle size greater than an average particles
size of the silica and titania materials, discussed above. For
example, the spacer particles in this embodiment are sol-gel
silicas. Examples of such sol-gel silicas include, for example,
X24, a 120 nm sol-gel silica surface treated with
hexamethyldisilazane, available from Shin-Etsu Chemical Co., Ltd.
In some embodiments, the spacer particles may have an average
particle size of from about 60 to about 300 nm, or from about 75 to
about 205 nm, such as from about 100 nm to about 150 nm.
[0048] In some embodiments, there are provided toner compositions
comprising toner particles and a plurality of additives disposed on
an exterior surface of the toner particles, the additives
comprising about 0.20 weight percent to about 0.50 weight percent
of uncoated particles having a density greater than or equal to
about 4.7 g/cm.sup.3 and a conductivity greater than or equal to
about 2.times.10.sup.-11 ohmcm.sup.-1, surface-treated silica,
surface-treated titania, and spacer particles, wherein the toner
composition is substantially free of one or more rare earth
compounds. In some such embodiments, the uncoated particles have an
average particle size in a range of from about 0.2 microns to about
1.0 microns. In some such embodiments, the toner particles are made
by an emulsion/aggregation coalescence process.
[0049] In some embodiments, there are provided toner compositions
comprising toner particles and a plurality of additives disposed on
an exterior surface of the toner particles, the additives
comprising uncoated particles satisfying the equation:
14.428-1.793.times.density
(g/cm.sup.3)-1,363,353.times.conductivity
(ohmcm.sup.-1).ltoreq.6
And surface-treated silica, surface-treated titania, and spacer
particles, wherein the toner composition is substantially free of a
rare earth compound and wherein the uncoated particles are present
in a sufficient amount to reduce bias charge roller contamination.
In some such embodiments, the uncoated non particles are present in
a range of from about 0.20 weight percent to about 0.50 weight
percent. In some such embodiments, the toner particles are made by
an emulsion/aggregation coalescence process.
Toner Particles
[0050] Suitable examples of toner latex resins or polymers may
include non-crosslinked resin and crosslinked resin or gel
combinations including, but not limited to, styrene acrylates,
styrene methacrylates, butadienes, isoprene, acrylonitrile, acrylic
acid, methacrylic acid, beta-carboxy ethyl acrylate, polyesters,
polymers such as poly(styrene-butadiene), poly(methyl
styrene-butadiene), poly(methyl methacrylate-butadiene), poly(ethyl
methacrylate-butadiene), poly(propyl methacrylate-butadiene),
poly(butyl methacrylate-butadiene), poly(methyl
acrylate-butadiene), poly(ethyl acrylate-butadiene), poly(propyl
acrylate-butadiene), poly(butyl acrylate-butadiene),
poly(styrene-isoprene), poly(methyl styrene-isoprene), poly(methyl
methacrylate-isoprene), poly(ethyl methacrylate-isoprene),
poly(propyl methacrylate-isoprene), poly(butyl
methacrylate-isoprene), poly(methyl acrylate-isoprene), poly(ethyl
acrylate-isoprene), poly(propyl acrylate-isoprene), poly(butyl
acrylate-isoprene); poly(styrene-propyl acrylate),
poly(styrene-butyl acrylate), poly(styrene-butadiene-acrylic acid),
poly(styrene-butadiene-methacrylic acid), poly(styrene-butyl
acrylate-acrylic acid), poly(styrene-butyl acrylate-methacrylic
acid), poly(styrene-butyl acrylate-acrylonitrile),
poly(styrene-butyl acrylate-acrylonitrile-acrylic acid), and the
like. In some embodiments, the resin or polymer is a styrene/butyl
acrylate/carboxylic acid terpolymer. In some embodiments, at least
one of the resins is substantially free of crosslinking and the
crosslinked resin comprises carboxylic acid in an amount of about
0.05 to about 10 weight percent based upon the total weight of the
resin substantially free of crosslinking or crosslinked resin.
[0051] In some embodiments, the resin used in forming the toner
particles can be one type of resin, or a mixture or combination of
two or more types of resins. For example, a single resin
(non-crosslinked or crosslinked) can be used to form the toner
particles. Alternatively the toner particles can be formed by using
a mixture of two or more resins, which are added together or
separately, at the same time or not, during the toner particle
formation process. In some embodiments, the resin used comprises
two resins, one of which is non-crosslinked and the other of which
is crosslinked.
[0052] In some embodiments, the resin that is substantially free of
crosslinking (also referred to herein as a non-crosslinked resin)
comprises a resin having less than about 0.1 percent crosslinking.
For example, the non-crosslinked latex comprises in some
embodiments styrene, butylacrylate, and beta-carboxyethylacrylate
(beta-CEA) monomers, although not limited to these monomers. Resin
particles may be formed de novo by emulsion polymerization in the
presence of an initiator, a chain transfer agent (CTA), and
surfactant.
[0053] In some embodiments, the resin substantially free of
crosslinking comprises styrene:butylacrylate:beta-carboxy
ethylacrylate wherein, for example, the non-crosslinked resin
monomers are present in an amount from about 70% to about 90%
styrene, about 10% to about 30% butylacrylate, and about 0.05 parts
per hundred to about 10 parts per hundred beta-CEA, or about 3
parts per hundred beta-CEA, by weight based upon the total weight
of the monomers, although not so limited. Other acrylate-based
resins may comprise, without limitation, acrylic acid, methacrylic
acid, itaconic acid, beta carboxyethyl acrylate (beta CEA), fumaric
acid, maleic acid, and cinnamic acid.
[0054] In particular embodiments, the non-crosslinked resin may
comprise about 73% to about 85% styrene, about 27% to about 15%
butylacrylate, and about 1.0 part per hundred to about 5 parts per
hundred beta-CEA, by weight based upon the total weight of the
monomers although the compositions and processes are not limited to
these particular types of monomers or ranges. In other embodiments,
the non-crosslinked resin may comprise about 81.7% styrene, about
18.3% butylacrylate and about 3.0 parts per hundred beta-CEA by
weight based upon the total weight of the monomers.
[0055] Emulsion polymerization initiators may include, without
limitation, sodium, potassium or ammonium persulfate and may be
present in the range of, for example, about 0.5 to about 3.0
percent based upon the weight of the monomers, although not
limited. The CTA may be present in an amount of from about 0.5 to
about 5.0 percent by weight based upon the combined weight of the
monomers, although it is not so limited. In some embodiments, the
surfactant may comprise an anionic surfactant present in the range
of about 0.7 to about 5.0 percent by weight based upon the weight
of the aqueous phase, although it is not limited to this type or
range.
[0056] By way of example, the monomers may be polymerized under
starve fed conditions as disclosed in U.S. Pat. Nos. 6,447,974,
6,576,389, 6,617,092, and 6,664,017, which are hereby incorporated
by reference herein in their entireties, to provide latex resin
particles having a diameter in a range from about 100 to about 300
nanometers. In some embodiments, the molecular weight of the
non-crosslinked latex resin may be in a range from about 30,000 to
about 37,000, or up to about 34,000, although it is not limited to
this range.
[0057] In some embodiments, the onset glass transition temperature
(T.sub.g) of the non-crosslinked resin may be in the range from
about 46.degree. C. to about 62.degree. C., or about 58.degree. C.,
although it is not so limited. In some embodiments, the amount of
acrylate-based monomers may be in a range of from about 0.04 to
about 4.0 ppb of the resin monomers, although it is not so limited.
In some embodiments, the number average molecular weigth (Mn) may
be in a range of from about 5000 to about 20,000, or about 11,000
daltons. In some embodiments, the prepared non-crosslinked latex
resin has a pH of about 1.0 to about 4.0, or about 2.0.
[0058] In some embodiments, a crosslinked latex is prepared from a
non-crosslinked latex comprising styrene, butylacrylate, beta-CEA,
and divinyl benzene, by emulsion polymerization, in the presence of
an initiator such as a persulfate, a CTA, and a surfactant. In some
embodiments, the crosslinked resin monomers may be present in a
ratio of about 60% to about 75% styrene, about 40% to about 25%
butylacrylate, about 3 parts per hundred to about 5 parts per
hundred beta-CEA, and about 3 parts per hundred to about 5 parts
per hundred divinyl benzene, although not it is not so limited to
these particular types of monomers or ranges. Any of the
above-described monomers can also be used for forming the
crosslinked latex or gel, as desired.
[0059] In some embodiments, the monomer composition may comprise,
for example, about 65% styrene, 35% butylacrylate, 3 parts per
hundred beta-CEA, and about 1 parts per hundred divinyl benzene,
although the composition is not limited to these amounts. In some
embodiments, the T.sub.g (onset) of the crosslinked latex may be in
a range of from about 40.degree. C. to about 55.degree. C., or
about 42.degree. C.
[0060] In some embodiments, the degree of crosslinking may be in a
range of from about 0.3 percent to about 20 percent, although it is
not so limited thereto, since an increase in the divinyl benzene
concentration may increase the crosslinking.
[0061] In some embodiments, a soluble portion of the crosslinked
latex may have a weight average molecular weight (Mw) of about
135,000 and a number average molecular weight (Mn) of about 27,000,
but it is not so limited thereto.
[0062] In some embodiments, the particle diameter size of the
crosslinked latex may be in a range of from about 20 to about 250
nanometers, or about 50 nanometers, although it is not so
limited.
[0063] In some embodiments, the surfactant may be any surfactant,
such as for example a nonionic surfactant or an anionic surfactant,
such as, but not limited to, Neogen RK or Dowfax, both of which are
commercially available. In some embodiments, the pH may be in a
range of from about 1.5 to about 3.0, or about 1.8.
[0064] In some embodiments, the latex particle size can be, for
example, from about 0.05 micron to about 1 micron in average volume
diameter as measured by the Brookhaven nanosize particle analyzer.
Other sizes and effective amounts of latex particles may be
selected in some embodiments.
[0065] The latex resins selected for forming toner particles may be
prepared, for example, by emulsion polymerization methods, and the
monomers utilized in such processes may include the monomers listed
above, such as, styrene, acrylates, methacrylates, butadiene,
isoprene, acrylonitrile, acrylic acid, and methacrylic acid, and
beta CEA. Known chain transfer agents, for example dodecanethiol,
in effective amounts of, for example, from about 0.1 to about 10
percent, and/or carbon tetrabromide in effective amounts of from
about 0.1 to about 10 percent, can also be employed to control the
resin molecular weight during the polymerization.
[0066] Other processes for obtaining resin particles of from, for
example, about 0.05 micron to about 1 micron can be selected from
polymer microsuspension process, such as the processes disclosed in
U.S. Pat. No. 3,674,736, the disclosure of which is incorporated
herein by reference in its entirety, polymer solution
microsuspension processes, such as disclosed in U.S. Pat. No.
5,290,654, the disclosure of which is incorporated herein by
reference in its entirety, mechanical grinding or milling
processes, or other known processes.
[0067] In some embodiments, toner particles may comprise a
polyester resin such as an amorphous polyester resin, a crystalline
polyester resin, and/or a combination thereof. The polymer used to
form the resin can be a polyester resin described in U.S. Pat. Nos.
6,593,049 and 6,756,176, the disclosures of each of which are
hereby incorporated by reference in their entirety. Suitable resins
also include a mixture of an amorphous polyester resin and a
crystalline polyester resin as described in U.S. Pat. No.
6,830,860, the disclosure of which is hereby incorporated by
reference in its entirety.
[0068] The resin can be a polyester resin formed by reacting a diol
with a diacid in the presence of an optional catalyst. For forming
a crystalline polyester, suitable organic diols include aliphatic
diols with from about 2 to about 36 carbon atoms, such as
1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol,
1,10-decanediol, 1,12-dodecanediol and the like; alkali
sulfo-aliphatic diols such as sodio 2-sulfo-1,2-ethanediol, lithio
2-sulfo-1,2-ethanediol, potassio 2-sulfo-1,2-ethanediol, sodio
2-sulfo-1,3-propanediol, lithio 2-sulfo-1,3-propanediol, potassio
2-sulfo-1,3-propanediol, mixture thereof, and the like. The
aliphatic diol may be, for example, selected in an amount of from
about 40 to about 60 mole percent, such as from about 42 to about
55 mole percent, or from about 45 to about 53 mole percent
(although amounts outside of these ranges can be used), and the
alkali sulfo-aliphatic diol can be selected in an amount of from
about 0 to about 10 mole percent, such as from about 1 to about 4
mole percent of the resin (although amounts outside of these ranges
can be used).
[0069] Examples of organic diacids or diesters including vinyl
diacids or vinyl diesters selected for the preparation of the
crystalline resins include oxalic acid, succinic acid, glutaric
acid, adipic acid, suberic acid, azelaic acid, sebacic acid,
fumaric acid, dimethyl fumarate, dimethyl itaconate, cis,
1,4-diacetoxy-2-butene, diethyl fumarate, diethyl maleate, phthalic
acid, isophthalic acid, terephthalic acid,
naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic
acid, cyclohexane dicarboxylic acid, malonic acid and mesaconic
acid, a diester or anhydride thereof; and an alkali sulfo-organic
diacid such as the sodio, lithio or potassio salt of
dimethyl-5-sulfo-isophthalate,
dialkyl-5-sulfo-isophthalate-4-sulfo-1,8-naphthalic anhydride,
4-sulfo-phthalic acid, dimethyl-4-sulfo-phthalate,
dialkyl-4-sulfo-phthalate, 4-sulfophenyl-3,5-dicarbomethoxybenzene,
6-sulfo-2-naphthyl-3,5-dicarbomethoxybenzene, sulfo-terephthalic
acid, dimethyl-sulfo-terephthalate, 5-sulfo-isophthalic acid,
dialkyl-sulfo-terephthalate, sulfoethanediol, 2-sulfopropanediol,
2-sulfobutanediol, 3-sulfopentanediol, 2-sulfohexanediol,
3-sulfo-2-methylpentanediol, 2-sulfo-3,3-dimethylpentanediol,
sulfo-p-hydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-amino ethane
sulfonate, or mixtures thereof. The organic diacid may be selected
in an amount of, for example, from about 40 to about 60 mole
percent, in embodiments from about 42 to about 52 mole percent,
such as from about 45 to about 50 mole percent (although amounts
outside of these ranges can be used), and the alkali
sulfo-aliphatic diacid can be selected in an amount of from about 1
to about 10 mole percent of the resin (although amounts outside of
these ranges can be used).
[0070] Examples of crystalline resins include polyesters,
polyamides, polyimides, polyolefins, polyethylene, polybutylene,
polyisobutyrate, ethylene-propylene copolymers, ethylene-vinyl
acetate copolymers, polypropylene, mixtures thereof, and the like.
Specific crystalline resins may be polyester based, such as
poly(ethylene-adipate), poly(propylene-adipate),
poly(butylene-adipate), poly(pentylene-adipate),
poly(hexylene-adipate), poly(octylene-adipate),
poly(ethylene-succinate), poly(propylene-succinate),
poly(butylene-succinate), poly(pentylene-succinate),
poly(hexylene-succinate), poly(octylene-succinate),
poly(ethylene-sebacate), poly(propylene-sebacate),
poly(butylene-sebacate), poly(pentylene-sebacate),
poly(hexylene-sebacate), poly(octylene-sebacate),
poly(decylene-sebacate), poly(decylene-decanoate),
poly(ethylene-decanoate), poly(ethylene dodecanoate),
poly(nonylene-sebacate), poly(nonylene-decanoate),
copoly(ethylene-fumarate)-copoly(ethylene-sebacate),
copoly(ethylene-fumarate)-copoly(ethylene-decanoate),
copoly(ethylene-fumarate)-copoly(ethylene-dodecanoate), alkali
copoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate), alkali
copoly(5-sulfoisophthaloyl)-copoly(propylene-adipate), alkali
copoly(5-sulfoisophthaloyl)-copoly(butylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkali
copoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate), alkali
copoly(5-sulfoisophthaloyl)-copoly(propylene-succinate), alkali
copoly(5-sulfoisophthaloyl)-copoly(butylenes-succinate), alkali
copoly(5-sulfoisophthaloyl)-copoly(pentylene-succinate), alkali
copoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate), alkali
copoly(5-sulfoisophthaloyl)-copoly(octylene-succinate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(butylene-sebacate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali
copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),
poly(octylene-adipate), wherein alkali is a metal like sodium,
lithium or potassium. Examples of polyamides include
poly(ethylene-adipamide), poly(propylene-adipamide),
poly(butylenes-adipamide), poly(pentylene-adipamide),
poly(hexylene-adipamide), poly(octylene-adipamide),
poly(ethylene-succinimide), and poly(propylene-sebecamide).
Examples of polyimides include poly(ethylene-adipimide),
poly(propylene-adipimide), poly(butylene-adipimide),
poly(pentylene-adipimide), poly(hexylene-adipimide),
poly(octylene-adipimide), poly(ethylene-succinimide),
poly(propylene-succinimide), and poly(butylene-succinimide).
[0071] The crystalline resin can be present, for example, in an
amount of from about 5 to about 50 percent by weight of the toner
components, such as from about 10 to about 35 percent by weight of
the toner components (although amounts outside of these ranges can
be used). The crystalline resin can possess various melting points
of, for example, from about 30.degree. C. to about 120.degree. C.,
in embodiments from about 50.degree. C. to about 90.degree. C.
(although melting points outside of these ranges can be obtained).
The crystalline resin can have a number average molecular weight
(Mn), as measured by gel permeation chromatography (GPC) of, for
example, from about 1,000 to about 50,000, such as from about 2,000
to about 25,000 (although number average molecular weights outside
of these ranges can be obtained), and a weight average molecular
weight (Mw) of, for example, from about 2,000 to about 100,000,
such as from about 3,000 to about 80,000 (although weight average
molecular weights outside of these ranges can be obtained), as
determined by Gel Permeation Chromatography using polystyrene
standards. The molecular weight distribution (Mw/Mn) of the
crystalline resin can be, for example, from about 2 to about 6, in
embodiments from about 3 to about 4 (although molecular weight
distributions outside of these ranges can be obtained).
[0072] Examples of diacids or diesters including vinyl diacids or
vinyl diesters used for the preparation of amorphous polyesters
include dicarboxylic acids or diesters such as terephthalic acid,
phthalic acid, isophthalic acid, fumaric acid, dimethyl fumarate,
dimethyl itaconate, cis, 1,4-diacetoxy-2-butene, diethyl fumarate,
diethyl maleate, maleic acid, succinic acid, itaconic acid,
succinic acid, succinic anhydride, dodecylsuccinic acid,
dodecylsuccinic anhydride, glutaric acid, glutaric anhydride,
adipic acid, pimelic acid, suberic acid, azelaic acid, dodecane
diacid, dimethyl terephthalate, diethyl terephthalate,
dimethylisophthalate, diethylisophthalate, dimethylphthalate,
phthalic anhydride, diethylphthalate, dimethylsuccinate,
dimethylfumarate, dimethylmaleate, dimethylglutarate,
dimethyladipate, dimethyl dodecylsuccinate, and combinations
thereof. The organic diacid or diester can be present, for example,
in an amount from about 40 to about 60 mole percent of the resin,
such as from about 42 to about 52 mole percent of the resin, or
from about 45 to about 50 mole percent of the resin (although
amounts outside of these ranges can be used).
[0073] Examples of diols that can be used in generating the
amorphous polyester include 1,2-propanediol, 1,3-propanediol,
1,2-butanediol, 1,3-butanediol, 1,4-butanediol, pentanediol,
hexanediol, 2,2-dimethylpropanediol, 2,2,3-trimethylhexanediol,
heptanediol, dodecanediol, bis(hydroxyethyl)-bisphenol A,
bis(2-hydroxypropyl)-bisphenol A, 1,4-cyclohexanedimethanol,
1,3-cyclohexanedimethanol, xylenedimethanol, cyclohexanediol,
diethylene glycol, bis(2-hydroxyethyl)oxide, dipropylene glycol,
dibutylene, and combinations thereof. The amount of organic diol
selected can vary, and can be present, for example, in an amount
from about 40 to about 60 mole percent of the resin, such as from
about 42 to about 55 mole percent of the resin, or from about 45 to
about 53 mole percent of the resin (although amounts outside of
these ranges can be used).
[0074] Suitable amorphous resins include polyesters, polyamides,
polyimides, polyolefins, polyethylene, polybutylene,
polyisobutyrate, ethylene-propylene copolymers, ethylene-vinyl
acetate copolymers, polypropylene, combinations thereof, and the
like. Examples of amorphous resins which may be used include alkali
sulfonated-polyester resins, branched alkali sulfonated-polyester
resins, alkali sulfonated-polyimide resins, and branched alkali
sulfonated-polyimide resins. Alkali sulfonated polyester resins may
be useful in embodiments, such as the metal or alkali salts of
copoly(ethylene-terephthalate)-copoly(ethylene-5-sulfo-isophthalate),
copoly(propylene-terephthalate)-copoly(propylene-5-sulfo-isophthalate),
copoly(diethylene-terephthalate)-copoly(diethylene-5-sulfo-isophthalate),
copoly(propylene-diethylene-terephthalate)-copoly(propylene-diethylene-5--
sulfoisophthalate),
copoly(propylene-butylene-terephthalate)-copoly(propylene-butylene-5-sulf-
oisophthalate), copoly propoxylated
bisphenol-A-fumarate)-copoly(propoxylated bisphenol
A-5-sulfo-isophthalate), copoly(ethoxylated
bisphenol-A-fumarate)-copoly(ethoxylated
bisphenol-A-5-sulfo-isophthalate), and copoly(ethoxylated
bisphenol-A-maleate)-copoly(ethoxylated
bisphenol-A-5-sulfo-isophthalate), wherein the alkali metal is, for
example, a sodium, lithium or potassium ion.
[0075] An unsaturated amorphous polyester resin can be used as a
latex resin. Examples of such resins include those disclosed in
U.S. Pat. No. 6,063,827, the disclosure of which is hereby
incorporated by reference in its entirety. Exemplary unsaturated
amorphous polyester resins include, but are not limited to,
poly(propoxylated bisphenol co-fumarate), poly(ethoxylated
bisphenol co-fumarate), poly(butyloxylated bisphenol co-fumarate),
poly(co-propoxylated bisphenol co-ethoxylated bisphenol
co-fumarate), poly(1,2-propylene fumarate), poly(propoxylated
bisphenol co-maleate), poly(ethoxylated bisphenol co-maleate),
poly(butyloxylated bisphenol co-maleate), poly(co-propoxylated
bisphenol co-ethoxylated bisphenol co-maleate), poly(1,2-propylene
maleate), poly(propoxylated bisphenol co-itaconate),
poly(ethoxylated bisphenol co-itaconate), poly(butyloxylated
bisphenol co-itaconate), poly(co-propoxylated bisphenol
co-ethoxylated bisphenol co-itaconate), poly(1,2-propylene
itaconate), and combinations thereof. A suitable polyester resin
can be a polyalkoxylated bisphenol A-co-terephthalic
acid/dodecenylsuccinic acid/trimellitic acid resin, or a
polyalkoxylated bisphenol A-co-terephthalic acid/fumaric
acid/dodecenylsuccinic acid resin, or a combination thereof.
[0076] Suitable crystalline resins that can be used, optionally in
combination with an amorphous resin as described above, include
those disclosed in U.S. Patent Application Publication No.
2006/0222991, the disclosure of which is hereby incorporated by
reference in its entirety. In embodiments, a suitable crystalline
resin can include a resin formed of dodecanedioic acid and
1,9-nonanediol. For example, a polyalkoxylated bisphenol
A-co-terephthalic acid/dodecenylsuccinic acid/trimellitic acid
resin, or a polyalkoxylated bisphenol A-co-terephthalic
acid/fumaric acid/dodecenylsuccinic acid resin, or a combination
thereof, can be combined with a polydodecanedioic
acid-co-1,9-nonanediol crystalline polyester resin.
Surfactants
[0077] In some embodiments, toner particles disclosed herein may be
formed in the presence of surfactants. For example, surfactants may
be present in a range of from about 0.01 to about 20, or about 0.1
to about 15 weight percent of the reaction mixture. Suitable
surfactants include, for example, nonionic surfactants such as
dialkylphenoxypoly-(ethyleneoxy) ethanol, available from
Rhone-Poulenc as IGEPAL CA-210.TM., IGEPAL CA-520.TM., IGEPAL
CA-720.TM., IGEPAL CO-890.TM., IGEPAL CO-720.TM., IGEPAL
CO-290.TM., IGEPAL CA-210.TM., ANTAROX 890.TM. and ANTAROX 897.TM..
In some embodiments, an effective concentration of the nonionic
surfactant may be in a range of from about 0.01 percent to about 10
percent by weight, or about 0.1 percent to about 5 percent by
weight of the reaction mixture.
[0078] Suitable anionic surfactants may include, without limitation
sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate,
sodium dodecylnaphthalene sulfate, dialkyl benzenealkyl, sulfates
and sulfonates, adipic acid, available from Aldrich, NEOGEN R.TM.,
NEOGEN SC.TM., available from Kao, Dowfax 2A1 (hexa
decyldiphenyloxide disulfonate) and the like, among others. For
example, an effective concentration of the anionic surfactant
generally employed is, for example, about 0.01 percent to about 10
percent by weight, or about 0.1 percent to about 5 percent by
weight of the reaction mixture
[0079] In some embodiments, anionic surfactants may be used in
conjunction with bases to modulate the pH and hence ionize the
aggregate particles thereby providing stability and preventing the
aggregates from growing in size. Such bases can be selected from
sodium hydroxide, potassium hydroxide, ammonium hydroxide, cesium
hydroxide and the like, among others.
[0080] Examples of additional surfactants, which may be added
optionally to the aggregate suspension prior to or during the
coalescence to, for example, prevent the aggregates from growing in
size, or for stabilizing the aggregate size, with increasing
temperature can be selected from anionic surfactants such as sodium
dodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate,
dialkyl benzenealkyl, sulfates and sulfonates, adipic acid,
available from Aldrich, NEOGEN R.TM., NEOGEN SC.TM. available from
Kao, and the like, among others. These surfactants can also be
selected from nonionic surfactants such as polyvinyl alcohol,
polyacrylic acid, methalose, methyl cellulose, ethyl cellulose,
propyl cellulose, hydroxy ethyl cellulose, carboxy methyl
cellulose, polyoxyethylene cetyl ether, polyoxyethylene lauryl
ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl
ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan
monolaurate, polyoxyethylene stearyl ether, polyoxyethylene
nonylphenyl ether, dialkylphenoxypoly(ethyleneoxy) ethanol,
available from Rhone-Poulenac as IGEPAL CA-210.TM., IGEPAL
CA-520.TM., IGEPAL CA-720.TM., IGEPAL CO-890.TM., IGEPAL
CO-720.TM., IGEPAL CO-290.TM., IGEPAL CA-210.TM., ANTAROX 890.TM.
and ANTAROX 897.TM.. For example, an effective amount of the
anionic or nonionic surfactant generally employed as an aggregate
size stabilization agent is, for example, about 0.01 percent to
about 10 percent or about 0.1 percent to about 5 percent, by weight
of the reaction mixture.
[0081] In some embodiments acids that may be utilized in
conjunction with surfactants to modulate pH. Acid may include, for
example, nitric acid, sulfuric acid, hydrochloric acid, acetic
acid, citric acid, trifluoroacetic acid, succinic acid, salicylic
acid and the like, and which acids are in embodiments utilized in a
diluted form in the range of about 0.5 to about 10 weight percent
by weight of water or in the range of about 0.7 to about 5 weight
percent by weight of water.
Waxes
[0082] In some embodiments, toner compositions may comprise a wax.
Suitable waxes for the present toner compositions include, but are
not limited to, alkylene waxes such as alkylene wax having about 1
to about 25 carbon atoms, polyethylene, polypropylene or mixtures
thereof. The wax is present, for example, in an amount of about 6%
to about 15% by weight based upon the total weight of the
composition. Examples of waxes include those as illustrated herein,
such as those of the aforementioned co-pending applications,
polypropylenes and polyethylenes commercially available from Allied
Chemical and Petrolite Corporation, wax emulsions available from
Michaelman Inc. and the Daniels Products Company, EPOLENE N-15.TM.
commercially available from Eastman Chemical Products, Inc., VISCOL
550-p.TM. a low weight average molecular weight polypropylene
available from Sanyo Kasei K.K., and similar materials. The
commercially available polyethylenes possess, it is believed, a
molecular weight (Mw) of about 1,000 to about 5,000, and the
commercially available polypropylenes are believed to possess a
molecular weight of about 4,000 to about 10,000. Examples of
functionalized waxes include amines, amides, for example Aqua
SUPERSLIP 6550.TM., SUPERSLIP 6530.TM. available from Micro Powder
Inc., fluorinated waxes, for example POLYFLUO 190.TM., POLYFLUO
200.TM., POLYFLUO 523.times.F.TM., AQUA POLYFLUO 41.TM., AQUA
POLYSILK 19.TM., POLYSILK 14.TM. available from Micro Powder Inc.,
mixed fluorinated, amide waxes, for example Microspersion 19.TM.
also available from Micro Powder Inc., imides, esters, quaternary
amines, carboxylic acids or acrylic polymer emulsion, for example
JONCRYL 74.TM., 89.TM., 130.TM., 537.TM., and 538.TM., all
available from SC Johnson Wax, chlorinated polypropylenes and
polyethylenes available from Allied Chemical and Petrolite
Corporation and SC Johnson Wax.
[0083] In some embodiments, the wax comprises a wax in the form of
a dispersion comprising, for example, a wax having a particle
diameter of about 100 nanometers to about 500 nanometers, water,
and an anionic surfactant. In embodiments, the wax is included in
amounts such as about 6 to about 15 weight percent. In embodiments,
the wax comprises polyethylene wax particles, such as Polywax 850,
commercially available from Baker Petrolite, although not limited
thereto, having a particle diameter in the range of about 100 to
about 500 nanometers, although not limited. The surfactant used to
disperse the wax is an anionic surfactant, although not limited
thereto, such as, for example, NEOGEN RK.TM. commercially available
from Kao Corporation or TAYCAPOWER BN2060 commercially available
from Tayca Corporation.
Pigments and Colorants
[0084] Toner compositions disclosed herein may further comprise a
pigment or colorant. Colorants or pigments as used herein include
pigment, dye, mixtures of pigment and dye, mixtures of pigments,
mixtures of dyes, and the like. For simplicity, the term "colorant"
as used herein is meant to encompass such colorants, dyes,
pigments, and mixtures, unless specified as a particular pigment or
other colorant component. In embodiments, the colorant comprises a
pigment, a dye, mixtures thereof, carbon black, magnetite, black,
cyan, magenta, yellow, red, green, blue, brown, mixtures thereof,
in an amount of about 1% to about 25% by weight based upon the
total weight of the composition. It is to be understood that other
useful colorants will become readily apparent to one of skill in
the art based on the present disclosures.
[0085] In general, useful colorants include, but are not limited
to, Paliogen Violet 5100 and 5890 (BASF), Normandy Magenta RD-2400
(Paul Uhlrich), Permanent Violet VT2645 (Paul Uhlrich), Heliogen
Green L8730 (BASF), Argyle Green XP-111-S (Paul Uhlrich), Brilliant
Green Toner GR 0991 (Paul Uhlrich), Lithol Scarlet D3700 (BASF),
Toluidine Red (Aldrich), Scarlet for Thermoplast NSD Red (Aldrich),
Lithol Rubine Toner (Paul Uhlrich), Lithol Scarlet 4440, NBD 3700
(BASF), Bon Red C (Dominion Color), Royal Brilliant Red RD-8192
(Paul Uhlrich), Oracet Pink RF (Ciba Geigy), Paliogen Red 3340 and
3871 K (BASF), Lithol Fast Scarlet L4300 (BASF), Heliogen Blue
D6840, D7080, K7090, K6910 and L7020 (BASF), Sudan Blue OS (BASF),
Neopen Blue FF4012 (BASF), PV Fast Blue B2G01 (American Hoechst),
Irgalite Blue BCA (Ciba Geigy), Paliogen Blue 6470 (BASF), Sudan
II, III and IV (Matheson, Coleman, Bell), Sudan Orange (Aldrich),
Sudan Orange 220 (BASF), Paliogen Orange 3040 (BASF), Ortho Orange
OR 2673 (Paul Uhlrich), Paliogen Yellow 152 and 1560 (BASF), Lithol
Fast Yellow 0991 K (BASF), Paliotol Yellow 1840 (BASF), Novaperm
Yellow FGL (Hoechst), Permanerit Yellow YE 0305 (Paul Uhlrich),
Lumogen Yellow D0790 (BASF), Suco-Gelb 1250 (BASF), Suco-Yellow
D1355 (BASF), Suco Fast Yellow D1165, D1355 and D1351 (BASF),
Hostaperm Pink E (Hoechst), Fanal Pink D4830 (BASF), Cinquasia
Magenta (DuPont), Paliogen Black L9984 9BASF), Pigment Black K801
(BASF) and particularly carbon blacks such as REGAL 330.RTM.
(Cabot), Carbon Black 5250 and 5750 (Columbian Chemicals), and the
like or mixtures thereof.
[0086] Additional useful colorants include pigments in water based
dispersions such as those commercially available from Sun Chemical,
for example SUNSPERSE BHD 6011.times. (Blue 15 Type), SUNSPERSE BHD
9312.times. (Pigment Blue 15 74160), SUNSPERSE BHD 6000.times.
(Pigment Blue 15:3 74160), SUNSPERSE GHD 9600.times. and GHD
6004.times. (Pigment Green 7 74260), SUNSPERSE QHD 6040.times.
(Pigment Red 122 73915), SUNSPERSE RHD 9668.times. (Pigment Red 185
12516), SUNSPERSE RHD 9365.times. and 9504.times. (Pigment Red 57
15850:1, SUNSPERSE YHD 6005.times. (Pigment Yellow 83 21108),
FLEXIVERSE YFD 4249 (Pigment Yellow 17 21105), SUNSPERSE YHD
6020.times. and 6045.times. (Pigment Yellow 74 11741), SUNSPERSE
YHD 600.times. and 9604.times. (Pigment Yellow 14 21095),
FLEXIVERSE LFD 4343 and LFD 9736 (Pigment Black 7 77226) and the
like or mixtures thereof. Other useful water based colorant
dispersions include those commercially available from Clariant, for
example, HOSTAFINE Yellow GR, HOSTAFINE Black T and Black TS,
HOSTAFINE Blue B2G, HOSTAFINE Rubine F6B and magenta dry pigment
such as Toner Magenta 6BVP2213 and Toner Magenta EO2 which can be
dispersed in water and/or surfactant prior to use.
[0087] Other useful colorants include, for example, magnetites,
such as Mobay magnetites MO8029, MO8960; Columbian magnetites,
MAPICO BLACKS and surface treated magnetites; Pfizer magnetites
CB4799, CB5300, CB5600, MCX6369; Bayer magnetites, BAYFERROX 8600,
8610; Northern Pigments magnetites, NP-604, NP-608; Magnox
magnetites TMB-100 or TMB-104; and the like or mixtures thereof.
Specific additional examples of pigments include phthalocyanine
HELIOGEN BLUE L6900, D6840, D7080, D7020, PYLAM OIL BLUE, PYLAM OIL
YELLOW, PIGMENT BLUE 1 available from Paul Uhlrich & Company,
Inc., PIGMENT VIOLET 1, PIGMENT RED 48, LEMON CHROME YELLOW DCC
1026, E.D. TOLUIDINE RED and BON RED C available from Dominion
Color Corporation, Ltd., Toronto, Ontario, NOVAPERM YELLOW FGL,
HOSTAPERM PINK E from Hoechst, and CINQUASIA MAGENTA available from
E.I. DuPont de Nemours & Company, and the like. Examples of
magentas include, for example, 2,9-dimethyl substituted
quinacridone and anthraquinone dye identified in the Color Index as
CI-60710, CI Dispersed Red 15, diazo dye identified in the Color
Index as CI-26050, CI Solvent Red 19, and the like or mixtures
thereof. Illustrative examples of cyans include copper
tetra(octadecyl sulfonamide) phthalocyanine, x-copper
phthalocyanine pigment listed in the Color Index as CI74160, CI
Pigment Blue, and Anthrathrene Blue identified in the Color Index
as DI 69810, Special Blue X-2137, and the like or mixtures thereof.
Illustrative examples of yellows that may be selected include
diarylide yellow 3,3-dichlorobenzidene acetoacetanilides, a monoazo
pigment identified in the Color Index as CI-12700, CI Solvent
Yellow 16, a nitrophenyl amine sulfonamide identified in the Color
Index as Foron Yellow SE/GLN, CI Dispersed Yellow 33
2,5-dimethoxy-4-sulfonanilide phenylazo-4'-chloro-2,4-dimethoxy
acetoacetanilide, and Permanent Yellow FGL. Colored magnetites,
such as mixtures of MAPICOBLACK and cyan components may also be
selected as pigments.
Coagulants
[0088] In some embodiments, toner compositions disclosed herein may
comprise a coagulant. In some embodiments, the coagulants used in
the present process comprise poly metal halides, such as
polyaluminum chloride (PAC) or polyaluminum sulfo silicate (PASS).
For example, the coagulants provide a final toner having a metal
content of, for example, about 400 to about 10,000 parts per
million. In another feature, the coagulant comprises a poly
aluminum chloride providing a final toner having an aluminum
content of about 400 to about 10,000 parts per million.
Toner Particle Preparation
[0089] In some embodiments, a toner process comprises forming a
toner particle by mixing a resin, such as a mixture or combination
of the non-crosslinked latex with a quantity of the crosslinked
latex, in the presence of a wax and a pigment dispersion to which
is added a coagulant of a poly metal halide such as polyaluminum
chloride while blending at high speeds such as with a polytron. The
resulting mixture having a pH of about 2.0 to about 3.0 is
aggregated by heating to a temperature below the resin Tg to
provide toner size aggregates. Optionally, additional
non-crosslinked latex is added to the formed aggregates providing a
shell over the formed aggregates. The pH of the mixture is then
changed by the addition of a sodium hydroxide solution until a pH
of about 7.0 is achieved. When the mixture reaches a pH of about
7.0, the carboxylic acid becomes ionized to provide additional
negative charge on the aggregates thereby providing stability and
preventing the particles from further growth or an increase in the
size distribution when heated above the Tg of the latex resin. The
temperature of the mixture is then raised to about 95.degree. C.
After about 30 minutes, the pH of the mixture is reduced to a value
sufficient to coalesce or fuse the aggregates to provide a
composite particle upon further heating such as about 4.5. The
fused particles are measured for shape factor or circularity, such
as with a Sysmex FPIA 2100 analyzer, until the desired shape is
achieved.
[0090] The mixture is allowed to cool to room temperature and is
washed. A first wash is conducted such as at a pH of about 10 and a
temperature of about 63.degree. C. followed by a deionized water
(DIW) wash at room temperature. This is followed by a wash at a pH
of about 4.0 at a temperature of about 40.degree. C. followed by a
final DIW water wash. The toner is then dried.
[0091] While not wishing to be bound by theory, in the present
toner composition comprising a non-crosslinked latex, a crosslinked
latex, a wax, and a colorant, the crosslinked latex is primarily
used to increase the hot offset, while the wax is used to provide
release characteristics. The ratio of the non-crosslinked latex to
the crosslinked latex, the wax content and the colorant content are
selected to control the rheology of the toner.
[0092] In some embodiments, the toner comprises non-crosslinked
resin, crosslinked resin or gel, wax, and colorant in an amount of
about 68% to about 75% non-crosslinked resin, about 6% to about 13%
crosslinked resin or gel, about 6% to about 15% wax, and about 7%
to about 13% colorant, by weight based upon the total weight of the
composition wherein a total of the components is about 100%,
although not limited thereto. In embodiments, the non-crosslinked
resin, the crosslinked resin or gel, the wax, and the colorant are
present in an amount of about 71% non-crosslinked resin, about 10%
crosslinked resin or gel, about 9% wax, and about 10% colorant, by
weight based upon the total weight of the composition.
[0093] In embodiments, the toner composition comprises a Mw in the
range of about 25,000 to about 40,000 or about 35,000, a Mn in the
range of about 9,000 to about 13,000 or about 10,000, and a Tg
(onset) of about 48.degree. C. to about 62.degree. C., or about
54.degree. C. In embodiments of the present toner composition, the
resultant toner possesses a shape factor of about 120 to about 140,
and a particle circularity of about 0.930 to about 0.980.
Composite Toner Particle
[0094] In embodiments, the colorant comprises a black pigment such
as carbon black. In yet another embodiment, the colorant is a
pigment comprising black toner particles having a shape factor of
about 120 to about 140 where a shape factor of 100 is considered to
be spherical and a circularity of about 0.900 to about 0.980 as
measured on an analyzer such as a Sysmex FPIA 2100 analyzer, where
a circularity of 1.00 is considered to be spherical in shape.
[0095] In another feature, the colorant comprises a pigment
dispersion, comprising pigment particles having a volume average
diameter of about 50 to about 300 nanometers, water, and an anionic
surfactant. For example, the colorant may comprise carbon black
pigment dispersion such as with Regal 300 commercially available,
prepared in an anionic surfactant and optionally a non-ionic
dispersion to provide pigment particles having a size of from about
50 nanometers to about 300 nanometers. In embodiments, the
surfactant used to disperse the carbon black is an anionic
surfactant such as Neogen RK.TM., or TAYCAPOWDER BN 2060, although
not limited thereto. In some embodiments, an ultimizer type
equipment is used to provide the pigment dispersion, although media
mill or other means can also be used.
[0096] Optionally, other various known colorants such as dyes or
pigments may be present in the toner and the toner can optionally
be used as an additional color in the xerographic engine besides
black and is selected in an effective amount of, for example, from
about 1 to about 65 percent by weight based upon the weight of the
toner composition, in an amount of from about 1 to about 15 percent
by weight based upon the weight of the toner composition, or in an
amount of from about 3 to about 10 percent by weight, for
example.
[0097] The combined additive package of uncoated particles, silica,
titania, and spacer particles are specifically applied to the toner
surface with the total coverage of the toner ranging from, for
example, as low as about 50% to as high as about 250% theoretical
surface area coverage (SAC), in some embodiments from about 55% or
about 70% to about 150 theoretical surface area coverage (SAC),
where the theoretical SAC (hereafter referred to as SAC) is
calculated assuming all toner particles are spherical and have a
diameter equal to the volume median diameter of the toner as
measured in the standard Coulter Counter method, and that the
additive particles are distributed as primary particles on the
toner surface in a hexagonal closed packed structure. Another
metric relating to the amount and size of the additives is the sum
of the "SAC.times.Size" (surface area coverage in percent times the
primary particle size of the additive in nanometers) for each of
the silica, titania, and spacer particles, or the like, for which
all of the additives should, more specifically, have a total
SAC.times.Size range of, for example, from about 500 to about
8,000, in embodiments from about 2,000 to about 5,000.
[0098] Thus, for example, in one embodiment, the additive package
for the toner composition comprises silica in an amount of from
about 1.8 to about 2.8 percent, titania in an amount of from about
1.5 to about 2.5 percent, and spacer particles in an amount of from
about 0.6 to about 1.8 percent, where the percentages are by
weight, based on a weight of the toner particles without the
additive. In another embodiment, the additive package for the toner
composition comprises silica in an amount of from about 1.9 to
about 2.0 percent, titania in an amount of from about 1.7 to about
1.8 percent, and spacer particles in an amount of from about 1.7 to
about 1.8 percent by weight. In some embodiments, additive package
for the toner composition comprises about 1.963 percent silica,
about 1.773 percent titania, and about 1.724 percent spacer
particles.
[0099] For further enhancing the positive charging characteristics
of the toner developer compositions, and as optional components
there can be incorporated into the toner or on its surface charge
enhancing additives inclusive of alkyl pyridinium halides,
reference U.S. Pat. No. 4,298,672, the disclosure of which is
totally incorporated herein by reference; organic sulfate or
sulfonate compositions, reference U.S. Pat. No. 4,338,390, the
disclosure of which is totally incorporated herein by reference;
distearyl dimethyl ammonium sulfate; bisulfates, and the like, and
other similar known charge enhancing additives. Also, negative
charge enhancing additives may also be selected, such as aluminum
complexes, like BONTRON E-88.RTM., and the like. These additives
may be incorporated into the toner in an amount of from about 0.1
percent by weight to about 20 percent by weight, and more
specifically from about 1 to about 3 percent by weight.
[0100] The toner compositions described herein are further
illustrated in the following examples. All parts and percentages
are by weight unless otherwise indicated.
[0101] It will be appreciated that some of the above-disclosed and
other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also, various presently unforeseen or unanticipated
alternatives, modifications, variations or improvements therein may
be subsequently made by those skilled in the art, and are also
intended to be encompassed by the following claims.
[0102] While the description above refers to particular
embodiments, it will be understood that many modifications may be
made without departing from the spirit thereof. The accompanying
claims are intended to cover such modifications as would fall
within the true scope and spirit of embodiments herein.
[0103] The presently disclosed embodiments are, therefore, to be
considered in all respects as illustrative and not restrictive, the
scope of embodiments being indicated by the appended claims rather
than the foregoing description. All changes that come within the
meaning of and range of equivalency of the claims are intended to
be embraced therein.
EXAMPLES
[0104] The examples set forth herein below and are illustrative of
different compositions and conditions that can be used in
practicing the present embodiments. All proportions are by weight
unless otherwise indicated. It will be apparent, however, that the
present embodiments can be practiced with many types of
compositions and can have many different uses in accordance with
the disclosure above and as pointed out hereinafter.
Example 1
[0105] A stress machine test (A-zone; high toner area coverage) was
developed that excacerbated the BCR contamination problem such that
screening of potential alternative additives to replace CeO.sub.2
could be done in a relatively short run machine test. Numerous
alternative materials were tested as potential CeO.sub.2
replacement additives to prevent the BCR contamination, but only a
few showed adequate performance. Of the alternative additives
tested, barium titanate (BaTiO.sub.3) demonstrated the excellent
performance for preventing BCR contamination. The following details
the testing and results.
[0106] A series of three emulsion aggregation high gloss (EA)
magenta parent toners were blended to compare the effectiveness of
different additives for preventing BCR contamination. Toner
blending was accomplished using a 10 L Henschel blender, and a
total of 1300 g toner was blended. The following three toners were
blended and loaded into separate toner cartridges: 1) Standard
magenta EA toner containing 0.55 weight percent E10 CeO.sub.2
additive as a control sample; 2) Magenta EA toner with 0.495 weight
percent BaTiO.sub.3 additive (Exprix Technologies, Sarasota, Fla.)
in place of CeO.sub.2; and 3) Magenta EA toner without E10
CeO.sub.2 or BaTiO.sub.3.
[0107] The toner cartridges were aged for one day in A-zone
conditions (85% relative humidity; at 32.degree. C.). The
cartridges were then loaded into three different color positions in
a printing machine. Machine testing was then done in A-zone,
running 5000 prints at 50% area coverage using the print pattern
shown in FIG. 1. This stress test highlighted BCR contamination in
a relatively short-run machine test.
[0108] Toner samples were removed at 1000 print intervals during
the test for analysis of chargeability (At), toner concentration
(TC), and visual inspection of any contamination of the BCR. After
5000 prints, the machine test was complete and the Customer
Replaceable Unit (CRU) was inspected for BCR contamination, as
exemplified in the photographs of FIG. 2. Significant additive
contamination, indicated by the white debris was observed on the
BCR when no additive was included in the formulation, while E10
CeO.sub.2 and BaTiO.sub.3 prevented contamination.
[0109] FIG. 3A shows toner charging (At) and FIG. 3B toner
concentration (TC) results that were measured at intervals
throughout the machine test for the additive-containing samples.
There was no significant difference in charging between the E10
CeO.sub.2 and BaTiO.sub.3 containing samples. These results
indicate that toner performance was not compromised by the
replacement of CeO.sub.2 with BaTiO.sub.3.
[0110] Outside of loading and the fact that the material is
specifically a BaTiO.sub.3 particle, other factors that contribute
to the practical usefulness of this toner additive include particle
size. The particle size is ideally not too small such that it does
not cause visually resolvable scratches on the photoreceptor as it
mills in the cleaning blade nip. Conversely, the particle size is
ideally not too large such that its surface energy is unable
overcome particle mass and adhere the particle to the parent toner.
Ideally, the BaTiO.sub.3 additive is free in the toner blend, so
that it tends not to transfer but rather accumulate at the blade
nip, where it can be effective at mitigating photoreceptor filming
and BCR contamination. To limit visually resolvable scratching on
the photoreceptor surface, an upper limit on average particle size
may be about 1 micron, and to limit surface energy compared to
particle mass, the lower limit on average particle size may be
about 0.2 microns.
[0111] This Example demonstrates that barium titanate can be used
instead of E10 CeO.sub.2 as a toner additive to prevent BCR
contamination and other important properties are not negatively
impacted. Replacement of CeO.sub.2 with barium titanate provides
significant cost savings and improved supply assurance for this
external toner additive.
[0112] Finally, it has been demonstrated that a number of other
non-rare earth additives can be used to replace cerium dioxide for
prevention of additive filming on the photoreceptor surface, but
only some of these additives are also capable of preventing BCR
contamination, as shown in the series of photographs in FIG. 4.
[0113] The claims, as originally presented and as they may be
amended, encompass variations, alternatives, modifications,
improvements, equivalents, and substantial equivalents of the
embodiments and teachings disclosed herein, including those that
are presently unforeseen or unappreciated, and that, for example,
may arise from applicants/patentees and others. Unless specifically
recited in a claim, steps or components of claims should not be
implied or imported from the specification or any other claims as
to any particular order, number, position, size, shape, angle,
color, or material.
[0114] All the patents and applications referred to herein are
hereby specifically, and totally incorporated herein by reference
in their entirety in the instant specification.
[0115] The claims, as originally presented and as they may be
amended, encompass variations, alternatives, modifications,
improvements, equivalents, and substantial equivalents of the
embodiments and teachings disclosed herein, including those that
are presently unforeseen or unappreciated, and that, for example,
may arise from applicants/patentees and others. Unless specifically
recited in a claim, steps or components of claims should not be
implied or imported from the specification or any other claims as
to any particular order, number, position, size, shape, angle,
color, or material.
[0116] All the patents and applications referred to herein are
hereby specifically, and totally incorporated herein by reference
in their entirety in the instant specification.
* * * * *